1 78 Management of Light in Illumination. 



windows have lately been furnished with double sashes ; 

 and the new outside sashes, which are nearly even with 

 the outside of the wall, have been glazed with ground 

 glass, the rough side of the glass being on the outside. 

 Since this has been done, the room has become incom- 

 parably more light and cheerful, notwithstanding that 

 the light which comes into it from without must now 

 pass through two panes of glass instead of one. 



There are many parlours and shops on ground floors 

 in narrow streets, that are so dark at mid-day as to be 

 scarcely habitable, which would be well lighted by the 

 adoption of this simple contrivance ; and rooms are so 

 much more warm and comfortable with double win- 

 dows, and the noise of the street is so effectually ex- 

 cluded by them, that these advantages alone would be 

 sufficient to recommend them ; but we see that they 

 may be made to furnish light as well as warmth and 

 quiet. 



There are many other situations in which ground 

 glass might be used with great advantage instead of 

 transparent glass ; but I must not enlarge on that sub- 

 ject in this place. Perhaps I may find some other occa- 

 sion of treating it more fully : in the mean time what 

 has been said may be useful as a hint to architects and 

 to those persons who are their own architects. 



I have lately made several experiments, in order to 

 see if ground glass could not be used for constructing 

 the screens of large pendulous illuminators; and from 

 the results of these trials I am inclined to think it may 

 be done. But as the large domes of gauze are so beau- 

 tiful, especially when they are ornamented with cut 

 glass, I shall be cautious how I propose any others till 

 I shall be perfectly sure they are preferable to them. 



